This invention relates to a method for providing a coated substrate. More particularly this invention relates to a method including applying an aqueous composition including an aqueous emulsion polymer, the polymer having a glass transition temperature (Tg) from xe2x88x9260xc2x0 C. to 80xc2x0 C., the polymer formed by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer, 0.1-50%, by weight based on the total weight of the polymer, ethylenically unsaturated aldehyde reactive group-containing monomer, and 0-7.5%, by weight based on the total weight of the polymer, ethylenically unsaturated acid monomer, in the presence of 0.01-1.0%, by weight based on the total weight of the polymer, t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms. And a method for improving the scrub resistance of a coating, a method for lowering the minimum film formation temperature of an aqueous coating composition, and a method for improving the adhesion of a coating to a substrate are provided.
The present invention serves to provide a method for providing a coated substrate including applying and drying an improved coating, by which is meant that the coating, xe2x80x9ccoatingxe2x80x9d herein including, for example, paint, topcoat, primer, paper coating, and leather coating, exhibits improvement in at least one of scrub resistance, marker stain blocking, exterior durability as indicated, for example, by gloss retention or cracking resistance, adhesion to substrates, water vapor permeability, and water swelling, relative to a coating in which an emulsion polymer of the same composition not so formed is employed.
U.S. Pat. No. 5,540,987 discloses emulsion polymers including at least 50% vinyl acetate having low residual formaldehyde and providing saturated cellulosic webs having improved tensile strength. The polymers are formed by the use of an hydrophobic hydroperoxide and ascorbic acid initiator throughout the course of the reaction.
The problem faced by the inventors is the provision of a method for providing a coated substrate, for improving the scrub resistance of a coating, for lowering the minimum film formation temperature of an aqueous coating composition, and for improving the adhesion of a coating to a substrate. Unexpectedly, the inventors found that the use of certain levels of t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms during the polymerization of a monomer mixture including aldehyde reactive group-containing monomers or even only in the last stages of the polymerization was sufficient to provide emulsion polymers which led to improved dry coatings properties.
In a first aspect of the present invention there is provided a method for providing a coated substrate including forming an aqueous coating composition comprising an aqueous emulsion polymer, the polymer having a glass transition temperature (Tg) from xe2x88x9260xc2x0 C. to 80xc2x0 C., formed by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer, 0.1-50%, by weight based on the total weight of the polymer, ethylenically unsaturated aldehyde reactive group-containing monomer, and 0-7.5%, by weight based on the total weight of the polymer, ethylenically unsaturated acid monomer in the presence of 0.01-1.0%, by weight based on the total weight of the polymer, t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms and, optionally, at least one other oxidant; applying the aqueous coating composition to the substrate; and drying, or allowing to dry, the aqueous composition.
In a second aspect of the present invention there is provided a method for improving the scrub resistance of a coating including forming an aqueous coating composition including an aqueous emulsion polymer, the polymer having a glass transition temperature (Tg) from xe2x88x9260xc2x0 C. to 80xc2x0 C., formed by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer, 0.1-50%, by weight based on the total weight of the polymer, ethylenically unsaturated aldehyde reactive group-containing monomer, and 0-7.5%, by weight based on the total weight of the polymer, ethylenically unsaturated acid monomer in the presence of 0.01-1.0%, by weight based on the total weight of the polymer, t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms and, optionally, at least one other oxidant; applying the aqueous coating composition to the substrate; and drying, or allowing to dry, the aqueous composition.
In other aspects of the present invention there are provided a method for lowering the minimum film formation temperature of an aqueous coating composition, a method for improving the adhesion of a coating to a substrate, and a method for improving the adhesion of a coating to an alkyd substrate.
This invention relates to a method including applying an aqueous coating composition including an aqueous emulsion polymer, the polymer having a glass transition temperature (Tg) from xe2x88x9220xc2x0 C. to 80xc2x0 C., formed by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer, 0.1-50%, by weight based on the total weight of the polymer, ethylenically unsaturated aldehyde reactive group-containing monomer, and 0-7.5%, by weight based on the total weight of the polymer, ethylenically unsaturated acid monomer in the presence of 0.01-1.0%, by weight based on the total weight of the polymer, t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms and, optionally, at least one other oxidant.
The aqueous emulsion polymer contains at least one copolymerized ethylenically unsaturated nonionic acrylic monomer. By xe2x80x9cnonionic monomerxe2x80x9d herein is meant that the copolymerized monomer residue does not bear an ionic charge between pH=1-14.
The ethylenically unsaturated nonionic acrylic monomers include, for example, (meth)acrylic ester monomers including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, lauryl acrylate, methyl methacrylate, butyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate. Other ethylenically unsaturated nonionic monomers which may be incorporated into the polymer include, for example, styrene and substituted styrenes; butadiene; vinyl acetate, vinyl butyrate and other vinyl esters; vinyl monomers such as vinyl chloride, vinyl toluene, and vinyl benzophenone; and vinylidene chloride. Preferred are all-acrylic, styrene/acrylic, and vinyl acetate/acrylic polymers. Preferred is a predominantly acrylic aqueous emulsion polymer. By xe2x80x9cpredominantly acrylicxe2x80x9d herein is meant that the polymer contains greater than 50%, preferably greater than 60%, by weight, copolymerized units deriving from (meth)acrylic monomers such as, for example, (meth)acrylate esters, (meth)acrylamides, (meth)acrylonitrile, and (meth)acrylic acid. The use of the term xe2x80x9c(meth)xe2x80x9d followed by another term such as acrylate or acrylamide, as used throughout the disclosure, refers to both acrylates or acrylamides and methacrylates and methacrylamides, respectively.
The emulsion polymer contains from 0.1% to 50%, by weight based on total monomer weight, of a copolymerized ethylenically-unsaturated aldehyde reactive group-containing monomer, based on the weight of the polymer. By xe2x80x9caldehyde reactive group-containing monomerxe2x80x9d is meant herein a monomer which, in a homogeneous solution containing 20% by weight of the monomer and an equimolar amount of formaldehyde at any pH from 1 to 14, will exhibit greater than 10% extent of reaction between the monomer and formaldehyde on a molar basis in one day at 25xc2x0 C. Included as ethylenically-unsaturated aldehyde reactive group-containing monomers are, for example, vinyl acetoacetate, acetoacetoxyethyl (meth)acrylate, acetoacetoxypropyl (meth)acrylate, allyl acetoacetate, acetoacetoxybutyl (meth)acrylate, 2,3-di(acetoacetoxy)propyl (meth)acrylate, vinyl acetoacetamide, acetoacetoxyethyl (meth)acrylamide, 3-(2-vinyloxyethylamino)-propionamide, N-(2-(meth)acryloxyethyl)-morpholinone-2,2-methyl-1-vinyl-2-imidazoline, 2-phenyl-1-vinyl-2-imidazoline, 2-(3-Oxazolidinyl)ethyl (meth)acrylate, N-(2-vinoxyethyl)-2-methyloxazolidine, 4,4-dimethyl-2-isopropenyloxazoline, 3-(4-pyridyl)propyl (meth)acrylate, 2-methyl-5-vinyl-pyridine, 2-vinoxyethylamine, 2-vinoxyethylethylene-diamine, 3-aminopropyl vinyl ether, 2-amino-2-methylpropyl vinyl ether, 2-aminobutyl vinyl ether, tert-butylaminoethyl (meth)acrylate, 2-(meth)acryloxyethyldimethyl-xcex2-propiobetaine, diethanolamine monovinyl ether, o-aniline vinyl thioether, (meth)acryloxyacetamido-ethylethyleneurea, ethyleneureidoethyl (meth)acrylate, (meth)acrylamidoethyl-ethyleneurea, (meth)acrylamidoethyl-ethylenethiourea, N-((meth)acrylamidoethyl)-N1-hydroxymethylethyleneurea, N-((meth)acrylamidoethyl)-N1-methoxymethylethyleneurea, N-formamidoethyl-N1-vinylethyleneurea, N-vinyl-N1-aminoethyl-ethyleneurea, N-(ethyleneureidoethyl)-4-pentenamide, N-(ethylenethioureido-ethyl)-10-undecenamide, butyl ethyleneureido-ethyl fumarate, methyl ethyleneureido-ethil fumarate, benzyl N-(ethyleneureido-ethyl) fumarate, benzyl N-(ethyleneureido-ethyl) maleamate, N-vinoxyethylethylene-urea, N-(ethyleneureidoethyl)-crotonamide, ureidopentyl vinyl ether, 2-ureidoethyl (meth)acrylate, N-2-(allylcarbamoto)aminoethyl imidazolidinone, 1-(2-((20hydroxy-3-(2-propenyloxy)propyl)amino)ethyl)-2-imidazolidinone, hydrogen ethyleneureidoethyl itaconamide, ethyleneureidoethyl hydrogen itaconate, bis-ethyleneureidoethyl itaconate, ethyleneureidoethyl undecylenate, ethylene ureidoethyl undecylenamide, 2-(3-methylolimidazolidone-2-yl-1)ethyl acrylate, N-acryloxyalkyl oxazolidines, acylamidoalkyl vinyl alkyleneureas, aldehyde-reactive amino group-containing monomers as dimethyaminoethyl methacrylate, and ethylenically unsaturated monomers containing aziridene functionality. Preferred is 0.5% to 20%, more preferred is 1% to 10%, by weight based on total monomer weight, of a copolymerized ethylenically-unsaturated aldehyde reactive group-containing monomer, based on the weight of the polymer.
In an alternative embodiment polymers containing a sufficient amount of copolymerized monomer(s) having reactive functionality, which is not reactive with aldehydes, to provide, after reaction during or after the emulsion polymerization, 0.1-50%, by weight based on the total weight of the emulsion polymer, copolymerized aldehyde-reactive monomer equivalent are also contemplated. By xe2x80x9ccopolymerized monomer equivalentxe2x80x9d is meant herein the copolymerized monomer which would have led to the copolymer even though the polymer was formed by a post-polymerization reaction rather than directly formed by the copolymerization of that monomer. In this embodiment, for example, the reaction product of polymers containing carboxylic acid functionality with compounds consisting of or containing an aziridine (ethyleneimine) ring or rings may be formed. Substitution on the ring may be on the nitrogen and/or either or both carbons such as, for example, ethyleneimine, propyleneimine, N-(2-hydroxyethyl) ethyleneimine, trimethylolpropane-tris-(xcex2-(N-aziridinyl) propionate), and pentaerythritol trimethylolpropane-tris-(xcex2-(N-aziridinyl) propionate). Also, polymers containing xcex2-aminoester and/ or xcex2-hydroxyamide functionality may be formed by post-polymerization processes.
The emulsion polymer contains from 0% to 7.5%, by weight based on total monomer weight, of a copolymerized monoethylenically-unsaturated acid monomer, based on the weight of the polymer, such as, for example, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, fumaric acid, maleic acid, monomethyl itaconate, monomethyl fumarate, monobutyl fumarate, maleic anhydride, 2-acrylamido-2-methylpropane sulfonic acid, vinyl sulfonic acid, styrene sulfonic acid, 1-allyloxy-2-hydroxypropane sulfonic acid, alkyl allyl sulfosuccinic acid, sulfoethyl (meth)acrylate, phosphoalkyl (meth)acrylates such as phosphoethyl (meth)acrylate, phosphopropyl (meth)acrylate, and phosphobutyl (meth)acrylate, phosphoalkyl crotonates, phosphoalkyl maleates, phosphoalkyl fumarates, phosphodialkyl (meth)acrylates, phosphodialkyl crotonates, and allyl phosphate.
The emulsion polymer used in this invention may contain from 0% to 1%, by weight based on monomer weight, copolymerized multi-ethylenically unsaturated monomers such as, for example, allyl methacrylate, diallyl phthalate, 1,4-butylene glycol dimethacrylate, 1,2-ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, and divinyl benzene.
The glass transition temperature (xe2x80x9cTgxe2x80x9d) of the emulsion polymer is measured by differential scanning calorimetry (DSC) taking the mid -point in the heat flow versus temperature transition as the Tg value, the monomers and amounts of the monomers being selected to achieve the desired polymer Tg range as is well known in the art. The preferred Tg of the emulsion polymer described hereinabove for use in coatings is from xe2x88x9260xc2x0 C. to 80xc2x0 C., more preferably from xe2x88x9210xc2x0 C. to 60xc2x0 C., most preferably from 0xc2x0 C. to 40xc2x0 C.
The polymerization techniques used to prepare aqueous emulsion-polymers are well known in the art. In the emulsion polymerization process conventional surfactants may be used such as, for example, anionic and/or nonionic emulsifiers such as, for example, alkali metal or ammonium salts of alkyl, aryl, or alkylaryl sulfates, sulfonates or phosphates; alkyl sulfonic acids; sulfosuccinate salts; fatty acids; ethylenically unsaturated surfactant monomers; and ethoxylated alcohols or phenols. The amount of surfactant used is usually 0.1% to 6% by weight, based on the weight of monomer. Either thermal or redox initiation processes may be used. The reaction temperature is maintained at a temperature lower than 120xc2x0 C. throughout the course of the reaction. Preferred is a reaction temperature between 30xc2x0 C. and 95xc2x0 C., more preferably between 50xc2x0 C. and 90xc2x0 C. The monomer mixture may be added neat or as an emulsion in water. The monomer mixture may be added in one or more additions or continuously, linearly or not, over the reaction period, or combinations thereof.
Conventional free radical initiators (oxidants) which may be used in addition to 0.01-1.0%, by weight based on the total weight of the polymer, t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms, preferably 0.01-1.0%, by weight based on the total weight of the polymer, t-alkyl hydroperoxide wherein the t-alkyl group includes at least 5 Carbon atoms; and more preferably 0.01-1.0%, by weight based on the total weight of the polymer, of t-amyl hydroperoxide include, for example, hydrogen peroxide, sodium peroxide, potassium peroxide, t-butyl hydroperoxide, cumene hydroperoxide, ammonium and/or alkali metal persulfates, sodium perborate, perphosphoric acid and salts thereof, potassium permanganate, and ammonium or alkali metal salts of peroxydisulfuric acid, typically at a level of 0.01% to 3.0% by weight, based on the weight of total monomer. Redox systems using one or more of the same initiators and a suitable reductant such as, for example, sodium sulfoxylate formaldehyde, ascorbic acid, isoascorbic acid, alkali metal and ammonium salts of sulfur-containing acids, such as sodium sulfite, bisulfite, thiosulfate, hydrosulfite, sulfide, hydrosulfide or dithionite, formadinesulfinic acid, hydroxymethanesulfonic acid, sodium 2-hydroxy-2-sulfinatoacetic acid, acetone bisulfite, amines such as ethanolamine, glycolic acid, glyoxylic acid hydrate, lactic acid, glyceric acid, malic acid, tartaric acid and salts of the preceding acids may be used. Redox reaction catalyzing metal salts of iron, copper, manganese, silver, platinum, vanadium, nickel, chromium, palladium, or cobalt may be used.
By xe2x80x9cin the presence of 0.01-1.0%, by weight based on the total weight of the polymer, t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atomsxe2x80x9d is meant that the cumulative amount of t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms which has been added to the reaction zone wherein at least some of the monomers are being converted to the emulsion polymer is 0.01-1.0%, by weight based on the total weight of the polymer; optionally wherein at least 95%, preferably the last 95%, by weight of the monomers are being converted to the emulsion polymer; optionally wherein at least 75%, preferably the last 75, by weight of the monomers are being converted to the emulsion polymer; optionally wherein at least the last 50% by weight of the monomers are being converted to the emulsion polymer; and optionally wherein at least the last 20% by weight of the monomers are being converted to the emulsion polymer. The optional additional oxidant includes those listed hereinabove as conventional free radical initiators such as, for example, tert-butylhydroperoxide, hydrogen peroxide, ammonium persulfate, and the like. In certain embodiments of the present invention, it is advantageous to choose a mixture containing one hydrophilic initiator and the relatively hydrophobic t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms in order to increase the overall efficiency of the initiator system with regard to the initiation of the full range of hydrophilic and hydrophobic monomers; preferably the optional additional oxidant(s) are less than 50% by weight of the total amount of initiator/oxidant. In this embodiment the t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms initator(s) and optional at least one other oxidant may be used as such or as the oxidant component(s) of a redox system using the same initiator(s) coupled with at least one suitable reductant such as those listed hereinabove.
In one embodiment, after 90-99.7%, preferably 95-99.7%, of the monomers by weight, based on the total weight of the polymer, have been converted to polymer, at least half of the remaining monomer is converted to polymer in the presence of 0.01-1.0%, by weight based on the total weight of the polymer, of t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms; preferably in the presence of 0.01-1.0%, by weight based on the total weight of the polymer, of t-alkyl hydroperoxide wherein the t-alkyl group includes at least 5 Carbon atoms; and more preferably in the presence of 0.01-1.0%, by weight based on the total weight of the polymer, of t-amyl hydroperoxide. This part of the reaction may be effected as soon as 90-99.7%, preferably 95-99.7%, conversion of the monomers to polymer is completed in the same reaction vessel or kettle. It may be effected after a period of time, in a different reaction vessel or kettle, or at a different temperature than the preceding part of the polymerization. Preferred is the presence of t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms only after 90%, more preferably only after 95%, conversion of the monomers to polymer is completed.
The t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms, optional additional oxidant(s), and optional reductant(s) may be added, for example, together or separately, in one or more shots or gradually, whether uniformly or not, or in combinations thereof or variations thereon as is desired; they may be added neat, in solution, or emulsified in an appropriate medium.
Chain transfer agents such as, for example, halogen compounds such as tetrabromomethane; allyl compounds; or mercaptans such as alkyl thioglycolates, alkyl mercaptoalkanoates, and C4-C22 linear or branched alkyl mercaptans may be used to lower the molecular weight of the formed polymer and/or to provide a different molecular weight distribution than would otherwise have been obtained with any free-radical-generating initiator(s). Linear or branched C4-C22 alkyl mercaptans such as n-dodecyl mercaptan and t-dodecyl mercaptan are preferred. Chain transfer agent(s) may be added in one or more additions or continuously, linearly or not, over most or all of the entire reaction period or during limited portion(s) of the reaction period such as, for example, in the kettle charge and in the reduction of residual monomer stage.
The emulsion polymer is also contemplated to be formed in two or more stages, the stages differing, for example, in composition and/or molecular weight.
The average particle diameter of the emulsion-polymerized polymer particles is preferred to be from 30 nanometers to 500 nanometers, as measured by a BI-90 Particle Sizer. Also contemplated are multimodal emulsion polymers in which at least two different particle sizes are included.
The aqueous composition is prepared by techniques which are well known in the coatings art. First, if the coating composition is to be pigmented, at least one pigment is well dispersed in an aqueous medium under high shear such as is afforded by a COWLES(copyright) mixer. Then the aqueous emulsion polymer is added under lower shear stirring along with other coating adjuvants as desired. Alternatively, the aqueous emulsion polymer may be included in the pigment dispersion step. The aqueous composition may contain conventional coating adjuvants such as, for example, tackifiers, pigments, emulsifiers, crosslinkers, coalescing agents, buffers, neutralizers, thickeners or rheology modifiers, humectants, wetting agents, biocides, plasticizers, antifoaming agents, colorants, waxes, and anti-oxidants.
The solids content of the aqueous coating composition may be from about 10% to about 85% by volume. The viscosity of the aqueous composition may be from 0.05 to 2000 Pa.s (50 cps to 2,000,000 cps), as measured using a Brookfield viscometer; the viscosities appropriate for different end uses and application methods vary considerably.
The aqueous composition may applied by conventional application methods such as, for example, brush or paint roller, air-atomized spray, air-assisted spray, airless spray, high volume low pressure spray, air-assisted airless spray, and electrostatic spray.
The aqueous composition may be applied to a substrate such as, for example, plastic including sheets and films, wood, metal, previously painted surfaces, weathered or aged substrates, cementitious substrates, and asphaltic substrates, with or without a prior substrate treatment such as a primer.
The aqueous composition coated on the substrate is typically dried, or allowed to dry, at a temperature from 20xc2x0 C. to 95xc2x0 C.
In one embodiment a method for improving the adhesion of a coating comprising a colloidally-stabilized emulsion polymer to an alkyd substrate, particularly to an aged or weathered alkyd substrate, is provided. By xe2x80x9ccolloidally-stabilizedxe2x80x9d emulsion polymer herein is meant an emulsion polymer prepared, at least in part, in the presence of a nonionic colloidal stabilizer. Without being bound by theory, it is believed that such a process results in the grafting of at least part of the colloidal stabilizer on the emulsion polymer with beneficial effect on the rheology of coatings prepared therefrom. The method of this invention includes forming an aqueous coating composition including (1) a first aqueous emulsion polymer including 0-2%, by weight based on the total weight of the first polymer, ethylenically unsaturated aldehyde reactive group-containing monomer, the first polymer having a glass transition temperature from xe2x88x9260xc2x0 C. to 80xc2x0 C. and a particle diameter of 200 to 1000 nanometers, prepared, at least in part, in the presence of 0.001-6%, by weight based on the dry weight of said first emulsion polymer, of a colloidal stabilizer selected from the group consisting of hydroxyethyl cellulose, N-vinyl pyrrolidone, polyvinyl alcohol, partially acetylated polyvinyl alcohol, carboxymethyl cellulose, gum arabic, and mixtures thereof, said colloidal stabilizer and (2) a second aqueous emulsion polymer, the second polymer having a glass transition temperature (Tg) from xe2x88x9260xc2x0 C. to 80xc2x0 C. and a particle diameter of 30 to 200 nanometers, formed by the free radical polymerization of at least one ethylenically unsaturated nonionic acrylic monomer, 0.1-12.5%, preferably 0.25-7.5%, by weight based on the total weight of the second polymer, ethylenically unsaturated aldehyde reactive group-containing monomer, and 0-7.5%, by weight based on the total weight of the polymer, ethylenically unsaturated acid monomer in the presence of 0.01-1.0%, by weight based on the total weight of the polymer, t-alkyl hydroperoxide, t-alkyl peroxide, or t-alkyl perester wherein the t-alkyl group includes at least 5 Carbon atoms and, optionally, at least one other oxidant, wherein the dry weight ratio of the second polymer to the first polymer is from 1:99 to 1:1; applying the aqueous coating composition to the alkyd substrate; and drying, or allowing to dry, the aqueous composition. The method provides adhesion improved relative to that engendered when a colloidally-stabilized emulsion polymer is used without the second emulsion polymer (the aqueous emulsion polymer used in this invention) in a corresponding aqueous coating composition.
The following examples are presented to illustrate the invention and the results obtained by the test procedures.
Abbreviations
MAA=methacrylic acid
BA=butyl acrylate
MMA=methyl methacrylate
AAEM=(2-acetoacetoxy)ethyl methacrylate
APS=ammonium persulfate
IAA=D-isoascorbic acid
t-BHP=t-butyl hydroperoxide
t-AHP=t-amyl hydroperoxide
DI water=deionized water